Childhood and adulthood passive and active smoking, and the ABO group as risk factors for pancreatic cancer in women.

OBJECTIVES: Active smoking and the A blood group are associated with pancreatic adenocarcinoma (PC) risk. However, potential interactions between those risk factors and the role of passive smoking have been little investigated. We aimed to explore specific and joint associations of passive and active smoking, and effect modification by the ABO blood group in French women. METHODS: The study included 96,594 women from the E3N prospective cohort, mean age: 49 years (SD 6.7). Information on active and passive smoking was reported at inclusion and throughout follow-up. Cases were classified according to the International Classification of Diseases 10. Associations with passive and active smoking and effect modification by the ABO blood group were investigated with multivariable Cox regression models to estimate hazard ratios (HR) and 95% confidence intervals (CI). RESULTS: During a 24-year median follow-up, 346 incident PC cases were identified. Current smoking compared with never and former smoking (HR 1.51 [95% CI 1.08-2.10]), and passive smoking in childhood compared with no childhood exposure (HR 1.47 [95% CI 1.08-2.00]) were associated with increased PC risk, but not passive exposure in adulthood (HR 1.16 [95% CI 0.91-1.47]). Exposure to both passive smoking in childhood and current smoking was associated with a stronger risk (HR 2.80 [95% CI 1.42-5.52]) than exposure to both current smoking and passive smoking only in adulthood (HR 1.68 [95% CI 1.10-2.57]) compared with neither passive nor active smoking. Associations between active smoking and PC risk were strongest in the O or B groups, while associations with passive smoking were strongest in the A or AB blood groups, but the interaction terms were not statistically significant. CONCLUSIONS: Both current smoking and passive smoking in childhood were associated with PC risk, with a maximal risk of current smokers exposed to passive smoking during childhood. Possible interactions between blood groups and active or passive smoking must be investigated in a larger series.